X-ray machines are widely applied in various fields such as health care, science education, industry, etc. The X-ray machine applied in the health care field is used to carry out imaging by irradiating X-rays onto a film after the X-rays penetrate the human body according to the fact that the densities of tissue structures such as muscle and bone are different.
When carrying out imaging on a patient, in order to obtain a clearer focus of the image and better image effect, a pressing device may be used. In order to make it convenient for the patient to get on or off the patient bed, the pressing device may be designed as one of two types of structure: a turnable pressing device or a foldable pressing device.
The turnable pressing device utilizes a guide control combining a helical groove with a linear groove, so that when the patient is getting on or off the patient bed, the pressing device turns to one side by way of the helical groove. When inspection is carried out, the pressing device enters into the linear groove by way of the helical groove so as to press on the organ of the patient.
A foldable pressing device may be assembled from several segments of structures. When the pressing device is lifted to a certain height, the pressing device starts to turn and fold in the same plane, making it easy for the patient to get on or off the patient bed. When the folded pressing device is descended to a certain position, the pressing device turns and unfolds again in the same plane, and is held in the unfolded state during the continuous descending motion, so as to carry out pressing on the patient.
The foldable pressing device is being used more, since the spatial utilization rate is high, the foldable pressing device is graceful in motion, and the potential risk is relatively small. The foldable pressing device is to realize multiple motions, and each motion has corresponding position requirements. The currently available foldable pressing devices may be controlled by more than two motors, resulting in that, for the foldable pressing devices in the prior art, both the structure and the motion control thereof are complicated. The price for the foldable pressing devices in the prior art is high, and the pressing device in the prior art may be used merely in some high-end products.
U.S. patent application US20080294264A1 discloses a shoulder type hinge, in which said shoulder type hinge includes a mechanical arm, and the mechanical arm is composed of an upper arm and a lower arm, the motions of the upper arm and the lower arm being coupled by two effectively connected rolling wheels.